DALLAS -- Lately Shawn Marion has shown that his nickname, The Matrix, has never fit better. The veteran forward's versatility to guard virtually any position on the floor is allowing the Dallas Mavericks to again start Jason Kidd and Vince Carter.

This aging combo was deemed not a workable backcourt pair after one half of the season opener simply because these once perennial All-Stars are a step slower defensively and together will find it tough to stay in front some of the league's quicker guard pairings. Particularly so against top point guards. In those cases, coach Rick Carlisle has typically used whichever player was starting at shooting guard to defend the point guard, while the 6-foot-4 Kidd would switch over to the opposing shooting guard.

If Vince Carter, and not the more compact and quicker Delonte West, is the starting shooting guard -- the spot he took over during Kidd's latest injury absence and has remained in his return -- the switcheroo isn't possible. The 6-foot-6 Carter can't defend the likes of Ricky Rubio or Chris Paul or, presumably, tonight's opponent, ultra-quick Denver Nuggets point guard Ty Lawson. Or -- gasp! -- Jeremy Lin on Sunday at Madison Square Garden.

Enter The Matrix.

"He’s been very consistent and his versatility in terms of our matchups, what’s needed, it gives us a dimension that not a lot of teams have," Carlisle said.

In just the last three games, Marion has played to near exhaustion in taking shifts against Rubio, Portland power foward LaMarcus Aldridge and Paul, who found Marion and double-teams draped all over him. Paul finished with 16 points, nine assists and five turnovers in Monday's Mavs win over the Clippers.

When asked to name another small forward in the game with the ability in one instance to body up against a 6-foot-11 power forward and in the next crank up the foot speed to cut off Paul's passing lanes, Carlisle said he couldn't.

It's why owner Mark Cuban has cranked up a Matrix-for-all-defensive-team campaign.

Asked if he believes he'll be start tonight's game guarding the 5-11 Lawson, the 33-year-old Marion, a bit wary himself of chasing around point guards all night, said he didn't think so. But, he might think twice about that.

"Look, we’re going to do what we need to do to try to keep teams at bay defensively, and some nights Shawn will be playing guys that are the smaller guys and some nights he’ll be guarding the [Kevin] Durants and the [Caron] Butlers of the world," Carlisle said. "I don’t think there’s any set formula. We’ve just got to be ready to play and guys got to be ready to adapt to situations that are presented to us."

But, these are the dilemmas for Dallas with a Kidd-Carter backcourt. If Carlisle sticks with them tonight, if Marion doesn't take Lawson then who does? And if Marion sticks Lawson, Kidd plays on Aaron Afflalo, that leaves the 35-year-old Carter against the springy 25-year-old Corey Brewer, who has started the last two games since his return from grieving his father's death.

Carter plays shooting guard and some small forward so guarding both positions isn't new. He said the Mavs will try to continue to go to the well as often as they can with Marion defending the point.

"He's a very good defensive player, moves his feet well, he just causes problems and he prides himself on that," Carter said. "He's very active and you've seen it in the last couple of games. That's a challenge that he accepts and he wants, so if he wants it we'll give it to him."